Remove RedisClient from MonitoringHandler

[mcweba]

The MonitoringHandler class provides methods to access the queueing functionality. Queue functionality is provided by the Redisques module and can be accessed through the EventBus.

Address.redisquesAddress().

In MonitoringHandler, the queueing functionality is directly accessed via the RedisClient. See example below:

redisClient.llen(queueName, reply -> {
    if(reply.failed()){
        log.error("Error gathering queue size for queue '" + queue + "'");
    } else {
        final long count = reply.result();
        vertx.eventBus().publish(Address.monitoringAddress(), new JsonObject().put(METRIC_NAME, prefix + LAST_USED_QUEUE_SIZE_METRIC).put(METRIC_ACTION, "update").put("n", count));
    }
});

This direct database access through the RedisClient should be omitted, because the correct way would be to use the Redisques module.
Maybe the Redisques module has to be extended to provide the needed information.